This is a copy-paste from an idea I had in another part of the forum. I've placed it here in separate as I am making it a house-rule.

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http://en.wikipedia.org/wiki/Lagrangian_point

These are points within system where gravity becomes null, and so their influence during Translation. They could be used in desperate times, but the chance of shocking against a planetary-warp-anomaly-correlative in the warp is still very likely.

A -10 Navigation-Stellar followed by a -60/-40 option for Navigation-Warp test for a Navigator to find an ideal Lagrangian point where translation in-out of the warp would be possible within a gravity well.

It also needs to take into account the size of the star and planets nearby, as their correlative in warp-space could smash the ship anyhow when it translates, so being able to do this should be rare.

For example: a system with a dim small white star that has 2 planetary bodies could have two Lagrangian point. But using the one closer to the start would inflict a -60 instead of -40 on the warp nav test due to the increased amount of warp anomalies/reefs representing being closer to the core.

Hm, how would this interact with the rules for emergency jumps from the Navigator/Astropath book?

I just want to point out that not the gravity is nullified at the L points - there is gravity force at that points -, only the gravity of stellar masses and the centrifugal force mutually nullify each other's effect. The gravity is an interpretable force connected to Warp travel - the centrifugal force is only interpretable within the stellar system of stellar masses.

All in all: I think to use the L points of a system you should take 2 things in consideration.

1. You should enter into real-space in a L point of the stellar system and

2. You should enter into the system with a certain speed and direction.

Thereby you can translate into the stellar system without the risk of deflection.

To translate this into game mechanics I think we should use the Core rulebook as a strong point: to enter into realspace at the precise coordinates the N should make a Navigation (Warp) check with -20. It is an additional -10 to find the L points of the system - which can be negated by a -30 Common lore (Koronus Expanse) or a -20 Navigation (Stellar) check - and another -10 to find the right direction and speed to enter. - which can be negated by a -30/-40 Pilot (Spacecraft) check. In sum the N should do a -20-10-10 = -40 Navigation (Warp) test to safely enter into a system's L point.

The Rogue Trader is the game of awesomeness and badassness - thereby it is not a problem to let the PCs do thing that any other (normal) imperial citizen wouldn't even think about

It was an epic moment of our Rak-Gol campaing when the Pride of the Emperor - in response to the desperate astropathic cry for help - immediately jumped near the upper atmosphere of Damaris to save the colony from the Rak-Gol bombardment and to deflect the firepower of Rak-Gol ships. It was an unfortunate case that half of augur arrays were melted away from the heat of friction when the ship was deflected off from the atmosphere.( Consequence of a barely botched Navigation (Warp) test to enter into real-space.)

These are points within system where gravity becomes null

That is not how Lagrange points work.

In fact common sense will immediately tell you that L2 experiences more gravitational pull than any other orbit of the same altitude.

The only one that might make sense is L1, but even then I am not sure. In fact I think it's still worse than approaching from the other side of the system if only for the fact that it's less like jumping face first into a shotglass of water.